Device for paddle wheel propellers



k June 21,1938. FSUBERKRUB 2,121,059

DEVICE FOR P ADDLE WHEEL PROPELILIERS Filed June 15, 1937 After/71. .96

Patented June 21, 19 38 PATENT OFFICE 2,121,059 DEVICE FOR PADDLE WHEEL PROPELLERS Franz Siiberkriib, Hamburg, Germany Application June 15, 1937, Serial No. 148,383

. In Germany June 18, 1936 2 Claims.

On a paddle wheel ship having paddle wheel propellers, the paddles of which are working alternately through the water and through the air, the direction of flow of the water around the paddle wheels shows a gradual contraction from forward to aft. In other words,the water has,

7 when arriving at the paddle wheel, a direction forming a certain angle with the direction of the ships course. If a paddle wheel towboat is moving with a speed of '7 statute .miles per hour (equal to about 10 feet per see.) through the water, the acceleration of the water is usually found to be also about feet per sec., so that the speed of the race in a certain distance behind T the paddle wheel, when seen from the ship, is

about feet per sec. The cross sectional area of the race, respectively of the water, which is set in motion by the action of the paddle wheel propeller therefore is about half as large behind 20 the wheel as in front of same. This hydrodynamic action is generally known for a fully immersed screw propeller of ships. In this latter case the contraction of the race has more or less a frustro-conical shape, the greatest area of the cone being at a certain distance infront of the propeller, the smallest at a certain distance behind same. The contraction of the race ona paddle wheel propeller, moving partly through the water and partly through the air, isdifierent since the cross sectional area of the racein this case is more or less rectangular and the conditions aside of the race are difiere-nt .from. those on a fully immersed screw propeller. On .a side wheel ship there is on one side of the race the vertical wall of the ships side while theupper side of the race forms the surface of the water. The contraction of the race therefore can take place from the free outside and from'below only. 40 Furthermore, since paddle wheel ships usually move in shallow water, the contraction of the race from below is limited by the distance of the bottom of the river underneath the paddles. In other words, the contraction takes place mostly from the free outside.

course, the contraction takes place from both sides, but in this case it can just as well ,be assumed thatthere is a central vertical separating wall between the two halves of the said stern wheel.

Basing on these considerations it will be seen that actually there is a very strongv contraction of the race from the outside towards the wheel, which may be observed quite plainly and measured quite simplyon each paddle wheel towboat'.

In a stern wheel ship, of

For usual towboat service-conditions it was found that near to the wheel, i. e. where the acceleration of the water is at its maximum, the direction of flow of the water and the centre line of the ship form an angle of about 15 degrees. The 5 side motion of the Water with respect to the direction of the ships course is a loss of propulsive efiiciency, since it does not produce any reaction in the direction of the ships movement.

It is the object of this invention to regain part 10 of this loss from the side motion of the water by arranging a vertical fin on the outside and rather close to the moving paddle wheel, by extending it into the water to about the same depth as the immersion of the paddles, by giving it the :15 profile of an airplane wing, the pressure side of l which is turned to the outside, and by fitting it to the ship respectively to its outside wheel box girder in such position to the movement of. the water, that it produces an additional pushing Q2 ioroe'in the direction of'the ships course. I By choosing a suitable shape of the profile and asuitable angular position of same with respect to the movement of the water it is possible to obtain with a rather small resistance a much 25 larger force actingrectangular to the direction of the flow of water, :said force being produced by the joint action of the pressure and suction side 0f the profile. This action is directly comparable to the air forces on a glider in the air, .30 :where'there is also the resistance of the wings, alifting and a driving force, and it is the driving force which in this particular case is pro- 'duced and transmitted by the vertical fin as additional pushing power onto the ship. It is 5 va'matter, of course, that the larger the angle is between the water moving towards the profile and the direction of the ships course the greater the additional pushing force will be which is transmitted by the fin onto the ship to which it is connected.

On'side wheel ships as well as on stern wheel beats .it is advisable to connect the fin tothe longitudinal bearer bars on the outside of the wheel or wheels which carry the wheel bearings. 45

In such cases where there are no outside bearings, as is sometimes found on side wheelboats, the fin is connected to the longitudinal bearer bar carrying the wheel box on the outside and aside of the moving paddles. 5 The accompanying drawing shows by way of example the vertical fin connected to the longitudinal girder on the outside of the wheel box of a side wheel boat. I

Figure 1 is a plan view showing the ships side, 55

ship, 2 the ships deck, 3 the bottom of the ship,

4 the shaft of the paddle wheel, 5 the outside bearing for said shaft, 6 the paddle wheel, 1 thesurface line of the water, indicating in Figure 2 at the same time the wave behind the paddle wheel when the wheel is moving, 8 the fin which is the main object of this invention, 9 transverse bearer bars and braces for the wheel box, H] the longitudinal bearer bar for the wheel box and the outside bearing (5) of the wheel and II the outline of the wheel box casing. The paddle wheel moves in the direction of the arrbws around its shaft 4. The direction of the water which is accelerated by the action of the wheel and moves towards same from forward and from the side is'indicated by the arrow marked Ve. I

If the vertical fin B, which is given the profile of an airplane wing, is connected to the ship in a suitable longitudinal and angular position to the direction of the incoming water Ve a free force S will be produced, acting as additional pushing power in the direction of the ships course.

How this force S is produced in this particular case is indicated by way of a diagram in Figure 1. The scheme. for this diagram is exactly the same as that which is customary for showing the forces, acting on an airplane wing.

The vis viva of the water moving in the direction Ve towards the profile 8 produces a resistance W. in line with the moving water and a lifting force A, which is measured vertically to the reaction W. The combined force of A and W is R which may be divided up again into the forces Q and S. Q is a transverse force rectangular to the direction of the ships course and does not therefore produce any additional thrust, while S is directed parallel and in the direction of the ships course and is therefore an additional thrust for driving the ship.

The size of the angle between Veand the centre line of the ship chiefly depends on the load on the paddles of the wheel, produced by the engine, and the speed of the ship. Therefrom follows that the shape of the profile, its size and its longitudinal and its angular position depend on the service conditions of the ship which for certain types of paddle wheel ships are more or less constant. On paddle wheel towboats, havingrather slow speeds through the water and high loads on the wheels, the size of the angle between Ve and the centre line of the ship will be rather large and consequently thick profiles may be used. Even with a somewhat negative angle between the pressure side of the profile and the direction of Ve a comparatively small resistance W" and a great lifting force A will be found. When on the other hand the load on the paddle wheel is small and the ships speed is large the profile of the fins 8 must be made rather slender.

As will be seen from Figure l a canal is formed between the profile 8 and the ships side I which is wide in front and narrows towards the rear in the direction of the movement of the water. Thereby the quantity of water which is guided towards the moving paddles and which is to be accelerated by same will be increased by the application of the fin. This increased quantity of water produces an increased efiiciency of the side wheel propeller.

When the load on the paddles is big the surface of the water between the immersed paddles sinks in, since the water from forward cannot follow quickly enough the acceleration produced by the paddles. This sinking in is equivalent to a decrease of the cross sectional area of the race,

or in other words, of the accelerated mass of water. The sinking in of the surface of the water therefore is responsible for a loss of efficiency. By increasing the quantity of water which is guided to the paddles, as is done by a properly shaped fin 8, the sinking in of the water may be eliminated and the full cross sectional area of the race will come into action.

These hydrodynamic conditions are comparable with the working conditions of a screw propeller for which is known, that the efiiciency of a large propeller with small acceleration is always better than that of a small propeller (small cross sectional'area of the race) and a big acceleration. Mass times acceleration=force What I claim is:

1. In combination with a paddle wheel propeller of a side wheel ship, having its paddles working alternately through the water and through the air, a vertical fin, arranged on the outside of said paddle wheel and extending into the water to about the same depth as the immersion of the paddles, said fin being fitted to the ships hull respectively to the girder, carrying the outsile wheel bearing of said paddle wheel, and having the profile of an airplane wing, the pressure side of which is turned to the outside.

2. In combination with a paddle wheel propeller of a stern wheel ship, having its paddles working alternately through the water and through the air, a vertical fin, arranged on each side of said paddle wheel and extending into the water to about the same depth as the immersion of thepaddleasaid fins'being fitted to the ships hull respectively to the girders carrying the wheel bearings of said paddle wheel and having the profile of an airplane wing, the pressure side of which is turned to the outside.

FRANZ st'IBERKRI'J'B. 

